Bonding
by Soapiepie
Summary: Set during CoLS. What if Sebastian had succeeded in making Clary drink from the Infernal Cup? How much will she change? Will she come to accept her brother?
1. Chapter 1

_"Drink," Sebastian said in a vicious whisper, so low she doubted Jace could hear it. "I told you by the end of the night you would do whatever I wanted. _Drink_." His black eyes darkened as he dug the cup in, slicing her bottom lip._

Clary screamed as the dark, vile fluid seeped into the cut and burned its way through her system. She could feel the poison fusing with her own blood, and a violent flood of nausea washed over her. Jace was behind her, supporting her, trying to sooth her with soft words. But it wasn't _her_ Jace, because _her_ Jace wouldn't sit back and watch Sebastian turn her—or anyone else—into a monster. Out of dizziness, as opposed to seeking comfort, Clary sank back against him. Her legs had turned to rubber at the thought that when Sebastian was finished with her, she would be a monster, just like him. Her mind reeled, rejecting the thought. Jace lowered her onto the ground, whispering to her soft words she couldn't comprehend.

Something cold and sharp dug against her numb lips. Sebastian was crouching in front of her, the Infernal Cup pressing against her mouth. He sat on her knees, effectively stopping her legs from moving. Clary jerked her head to the side. "Jace," she tried to say, in her last attempts to bring his real side back. "Jace, you have to stop him! Get him away from us!" She tried wrestling her arms free from his grip, her whole body thrashing violently with the effort. She gave up on Jace and screamed "HELP ME!" in a futile attempt to gain the attention of someone fighting below them. Unfortunately, while her mouth was wide open, Sebastian filled it with the acrid blood, immediately covering his free hand over her mouth and nose, forcing Clary to swallow. She slumped, her energy sapped from her as the poison burned through her system. Her body, still trying to reject the awful, bitter liquid, shut down. Like a giant, aggressive wave, the darkness crashed around Clary as she gave in, defeated, defenceless and alone.

XxXxXxXxXxXxXxXxXxX

At first Clary was conscious of nothing. Then a throbbing, burning pain, like a fire was raging within her. She tried to sit, but a jab of white-hot pain exploded from her chest. She screamed silently, unconsciousness creeping closer, threateningly. Then a cool piece of fabric was placed on her forehead. _Jace?_ She thought, _what happened? Oww, everywhere hurts_.

"Shh. I know it hurts, Clary." The voice was so loud Clary instinctively tried to cover her ears, only to cry out as more pain knifed through her. A stele traced the _iratze_ rune on the inside of her arm, and if it wasn't for the iron grip on her wrist Clary would have jerked away. It wasn't the usual sting, but instead a terrible slow burn which left her whole arm throbbing.

_Sorry, little sis, your senses appear to be extremely sensitive. _Clary gasped, now that the voice wasn't bursting her eardrums, she realised it was lovely; gentle and melodious and…_it was speaking inside her mind!_ "How are you doing that?" She croaked, glad that at least the _iratze_ had somewhat eased her senses. "Wait, you're not Jace…Sebastian?"

_Yours truly. I made a tisane for you which should calm your fever for a while. Here. _His hand slid to the back of her burning head and tilted it slightly. Something cold and sharp dug into Clary's lip and, momentarily ignoring the pain, she jerked away from it, as if there was some traumatic memory she related to the goblet. She moved her head back, embarrassed, and drank obediently. The tisane was smooth and rich and sweet, but slightly bitter, like dark chocolate. Clary found herself eagerly draining the goblet, enjoying the warmth that spread through her. The pain within her receded immediately, and she felt her head clear. "Mmm…what was that?" She asked contently.

Sebastian removed the cup and said, "When you first drank from the Infernal Cup, at the Ceremony, it was not just Great Mother Lilith's blood, but also my own. That has given us, among other things, a telepathic tendency."

She noticed he had failed to answer her question, instead leaving her to do her own deductions. _When I __first__ drank from the infernal cup…was that the goblet I just drank from?_ Sebastian laughed softly, as if he could hear her thoughts. _His blood? __**Was that "tisane" actually his blood? Did I just drink his…?**_But she was distracted from her mental raving when Sebastian slid his cool, calloused fingertips over her cheek, and then stroked her sweat-drenched hair off her face. Clary shivered at his touch, but found herself drawn to it, wanting more.

For a while she was so lost in the light caresses that she almost forgot it was Sebastian doing it. Sebastian her demonic, older brother. Sebastian, who had recently forced _his demon blood_ down her throat. She inhaled sharply, realizing she had completely forgotten about her boyfriend. She directed her thoughts to where she could feel Sebastian sitting on the bed in the darkness next to her. _Jace. Why isn't he here? Where's he?_

She felt him tense._ Easy there, Clary. You are focusing on it too much. Relax a little._

_Like this? _She thought, hesitantly, surprised when she felt him relax again.

"You are a natural at this, my Dear," he said, "I believe we were talking about Jace? There was a slight…complication following the ceremony. The group of Shadowhunters and their Downworlder-scum allies kidnapped him. They tried to get you too, but I would not let them touch you."

_What!?They took Jace!? You mean my family? Did you hurt any of the—_

_"I am your family!" _Sebastian hissed_ "I am the only one who matters!"_

Clary flinched at the abrupt harshness in his voice. She wanted desperately to hear his gentle, lulling voice again. To calm him, she said, "I-I'm sorry, Seb. I didn't mean to offend you. I-I…" She trailed off, suddenly not sure what she was apologizing for. To her relief, he resumed the light stroking that Clary realized she'd begun to love. She shifted her head closer to his fingers and as if sensing her approval, Sebastian made a soft noise.

"The blood had a strange effect on you. I believe it could be because of the abnormal amounts of Angel blood Valentine pumped into you. It was like your system was rejecting it. The fever and pains you are experiencing at the present is an effect of this."

_Am I a monster like you now?_ She whispered inside his mind as the implications of what he had done to her sank in.

"Clarissa, we are not monsters, we are Morgensterns!"he spat, and left.


	2. Chapter 2

Clary woke again, sunlight streaming through her the window and the pain within her palliated, but with an aching feeling something was missing. She eased out of bed to the door, impatient at her immobility. Within her, a nagging sensation motivated her out of the room, down a flight of stairs, through the kitchen and finally, to a closed door. She opened it and stepped inside.

Sebastian looked up from examining a large tome which sat in front of him at a large steel-and-glass desk.

_Seb?_ Clary thought to herself, _he's the thing I was missing?_

"You missed me?" Clary jumped as she felt Sebastian's breath on her neck as he whispered the words into her ears. She marvelled at how stealthily he could move, sneaking up on her like that.

_I still hear your thoughts Clarissa dear, _he said mockingly, and chuckled quietly. His arms slipped around her waist, warm and comforting. She sank into his solid body, the part of her mind that had been nagging her now purring like Chairman Meow did when he was petted.

And for the second time in as many days, Clary yanked away from Sebastian, reprimanding herself for relaxing in his presence. She should be trying to get away from him, not seeking him out. He snarled, as if she had been speaking her thoughts aloud, and before she had time to react, he pounced with cat-like grace and knocked her down. Clary struggled desperately, remembering a similar time just before the ceremony, when he had first violated her personal space uncomfortably. But try as she might, Sebastian had already gotten a hold of her wrists in one of his hands, the other grinding the side of her face into the floorboards. With a razor-sharp claw, he sliced through the sleep-shirt she was wearing, exposing her bare back. Clary whimpered as the hand previously on her head began massaging between her shoulder blades, deceivingly gentle. He worked for a while, rubbing tight circles over the kinks and knots, not ceasing until they were all gone.

Clary hated how skilled his hands were. She hated it, but loved it at the same time, and then hated herself for loving it at all. She could feel herself relenting, calming to his touch, even though she could tell he was about to do something terrible to her and was only comforting her so that his next move wouldn't be expected. And even though she anticipated it, the cool sting of the stele made her jump. Then the weight of Sebastian's body left her, and she scrambled to her feet, backing away from him as fast as her disorientated self could.

"What rune was that?" Clary asked warily.

"I just Marked you as mine, Sister Dear. Not a binding rune; you already have my blood within you. You are now my mate, my queen," he said, almost-reverently, calmly returning to his desk.

"WHAT THE FUCK!? YOU FUCKING ASSHOLE! YOU SICK, TWISTED—" She screamed, collapsing as the most excruciating pain clawed through her body.

"I am your demon sire, and your life-mate. You belong to me now, and you cannot insult me in that way. Let's try again shall we? Come here, Clarissa." His tone left no room for argument, but Clary preferred to be out of his arm's reach. "No," she whispered, noticing the flash of irritation within his onyx eyes. Her satisfaction was short-lived as it was moments later that Clary was returned to the same agony as before.

Finally, the pain receded, and Sebastian, as impassive as ever, said, "You cannot disobey me, Clarissa; you will not be able to. Your inner demon—if you will—won't let you. Come here."

For a split-second, Clary considered stalling again, but her brain easily decided against it. Pitifully, she dragged herself on useless limbs to her captor. When she reached his feet, a blissful, deep pleasure filled every aching crevice of her body.

His voice was suddenly soothing, "But if—and when—you obey me, sweet sister, you reward yourself. That pleasure is no coincidence, Clarissa." Sebastian crouched down and, picking her up off the floor, carried her to her room.

Clary hadn't made her bed when she left it, and Sebastian lay her down and pulled the sheets around her, tucking her in snugly, as if she was a little girl. He turned to leave, but Clary whispered; "Seb, how do I avoid the pain?"

He leant down and kissed her hair, then perched on the edge of her bed. He smoothed her flame-coloured mane, tucking a stray curl behind her ear before saying; "You must learn to be submissive to me, little sister. You must respond to my calls without hesitation. When I say your name, you must cease whatever you are doing, come to me, and give me your undivided attention." His voice slipped into the soft, caressing tone he had used when she was feverous, "You are a clever girl, and as long as you contain that fiery temper, and continue consuming my blood, you will soon find it easy to do my bidding. That is not too demanding of me, is it Clarissa?"

"N-No." Even though her answer was hesitant, he smiled a lovely, charming smile at her answer, kissed her cheek, and straightened. "But Seb?" Clary murmured, realising she _really_ didn't want him to leave. When he turned back around, she asked; "Can you please stay with me, at least until I fall asleep?"

He obliged, and she shuffled over to give him more space. Sebastian wrapped his arms around her possessively, soothing her with whispered soft nothings and feather-light caresses. Worn, she accepted his affection with a new-found tolerance. Having not fully recovered, Clary was already exhausted from her most recent ordeals, but her brain whirred away, not allowing her to sleep. _This link between Sebastian and I is what must be causing the periods of time where I am extremely attracted to him. When I completely forget about Jace, my family, my friends. When I forget that Sebastian is a sick, twisted demon who is holding me prisoner, who has fed me his blood twice now, who just bound me to him and who is my brother for crying out loud! __Not to mention my own disgusting self who, although linked with the freak, sometimes actually likes it!?_

_I really should punish you for thinking those things, Clarissa, but I feel you are starting to trust me. _He grinned, _possibly even like me._

"You say that _after_ I called you all those things?" Clary sighed, "I suppose you can read my mind then?"

_You seemed more self-deprecating._

"You have an ego like the Idris Towers; big, deflecting and indestructible. Don't flatter yourself," Clary quipped, earning a hard-fought grin from her older brother.

_I did strip the wards off Idris recently, little one, you were there. Deflecting?_

"The wards stop mundanes from finding Alicante; likewise you never answer my questions," She said, snuggling closer to him. Sebastian kissed her temple and slipped his fingers onto her navel, his fingertips swirling across the smooth skin there. Clary only just managed to supress the groan which very nearly escaped her lips. "Now you're trying to distract me," Clary gasped. "Wait a second…did you just call me _little one?_"

_If I did? _Sebastian all but purred, and slipped his fingers higher, making Clary shudder.

"S-Stature wise?" Clary asked, failing to stop her voice from quivering too much. She reproached herself for reacting to his touch far too well. "Because then, that is _very not _alright"

He laughed softly, "I suppose your height—or lack of it—" Clary punched his chest, "—is bully-worthy." He sobered astonishingly quickly, his arms tightening around her protectively. "Was there anyone who ever upset you, Clarissa? Let me punish them for you. Let me hurt them, for hurting you."

"Seb. Please don't. It really doesn't matter." Clary gasped as his arms tensed further, squeezing the air from her. _He hurt me. Sebastian made me into a monster, a demon. I don't really know what I am; with copious amounts of angel and demon blood, am I even human anymore? Will he punish himself for me? Huh, doubt it. I don't even know if my friends will accept me or can change me back into a normal person when they come and rescue me. Oh, Jace! Simon! Izzy! Alec! Mum! Luke—_

Sebastian growled, striking her cheek hard, leaving a stinging redness that clashed with her flaming hair. Her body didn't even have the energy to react to it, let alone fight back. Clary hated herself for being so pathetic. She realised she was so wrapped up in Sebastian that she had not even searched the apartment, looked out a window, found a front door or a stele. But she knew why; at least part of her _did not want to leave_, and it bothered her that she didn't mind. Clary knew that her changing had barely started; that her conflicting emotions and thoughts would dissipate with time that the demon inside her would possess her and she would be like Jace when he was bound to Sebastian.

"If you aren't going to rest then make yourself useful. Follow," Sebastian snarled at her. Clary numbly got out of her bed and followed him, regretting she had upset him, longing for the atmosphere of their conversation minutes ago. For a while, Clary was able to forget that there was anything twisted about her relationship with her brother. For a while they were joking, and teasing, and _getting along_.


	3. Chapter 3

Clary followed her brother down the corridor to the room next to his study. With her artist's eye, she studied the way he moved; graceful, lithe and awfully, painfully similar to Jace.

The room was impossibly large for the apartment, with shelves and shelves of books, tomes and scrolls. It also appeared to be multiple storeys high, with ornate, winding staircases leading to balconies, past which Clary couldn't see. She gasped, "This is like that blue box from that show Simon's obsessed with!"

Annoyed, Sebastian ignored her, probably not understanding the reference or bothering to comment snidely on Clary's nerdy best-friend. In the centre of the room was a podium with an old-blood coloured book. Sebastian picked it up and handed it to Clary. The book was leather-bound with thick, yellowed leaves. She flipped through it to find elaborate handwritten script and beautiful, old paintings. The images were all in reds and oranges, depicting destruction and Hell.

"When I am occupied, you will come here and read a text I will have assigned you previously. You can start with this. It is the Book of Revelations, the only useful part of the Christian Bible. You will read this, Clarissa, because it is vital you truly understand our plans, and accept them. When you have finished, you will find me in my study and recite it to me. If you fail to return to my study by an appropriate time, I will come and find you."

Clary opened it to the first page, but couldn't work out what the script said. Then she realised, "This isn't in English!" She shouted at the retreating figure of her older brother. Without turning, he called back, "By the Angel, I always seem to forget how little useful information they teach you mundanes," he sneered. "It is Ancient Greek, sister." _Ancient Greek? That is so unfair! _"I can't even read normal Greek!" Clary yelled. Finally Sebastian looked around at her and said, in an infuriatingly calm voice, "You are in a library, Clarissa. Go figure." The door slammed behind him.

XxXxXxXxXxXxXxXxXxX

Slightly less than an hour later, the door opened. Without looking up, Clary, in tears of frustration, shouted, "An hour is a really 'appropriate time' for anyone to learn a whole extinct language and read a book!"

"Pardon me, Mistress," a raspy, toneless voice croaked. Clary shrieked, expecting Sebastian's drawl. A rigid Amatis Herondale stood at the open door, wearing simple black work pants and shirt, holding a delicate tea set balanced on a silver tray. Clary sobbed when she saw Luke's sister.

_**Jonathan Christopher Morgenstern!**_ She screamed in his mind, _**Sebastian, that is sick! That is low, even for you! Why would you make her serve me?**_

_Fuck, Clarissa! My brain is vibrating in my head!_

_**As if you can feel anything, you monster!**_

_Can you please calm down? By the Angel, Clarissa, just tell Amatis to leave!_

_**I'll kill you for that! How dare you defile Amatis Herondale's name! Was killing her and replacing her with this demon thing not enough for you? How could I ever love you, when you can't even feel a damn thing!? I could never love a monster like you! I hate yo— **_Clary screamed as pain slashed through her body, shredding her insides, dizziness and nausea like machine-gun ammunition, tearing at her. She waited for it to finish, but the wave did not end; just went on and on, every second, a decade, every decade, infinity.

Finally, Clary collapsed, her body battered, cracked, broken. Darkness crashed around her like curtains signalling the end of a play.


	4. Chapter 4

She wasn't in her bed. The bedding felt like it was made of the finest silk, and Clary couldn't stop herself from sliding her arms up and down the slippery, extravagant material. The second thing she noticed was the lemon-pepper scent that overwhelmed her. Instinctively, she thought of Jace, but castigated her own misjudgement; she had almost forgotten Jace and Sebastian had the same cologne. Hurriedly, she stopped herself from thinking about her boyfriend, Jace, because of the harrowing pain that always swamped her when she remembered Sebastian still divided them.

In the moments of her near-wakefulness, Clary rolled around to face the warm, sleeping form of her brother in the pre-dawn light. She reached up dreamily, her fingers drifted through his fine hair. He seemed so peaceful asleep, not like the furious, demonic side of him that, just yesterday, had punished her with Amatis' infernal ghost.

Sebastian turned onto his back, making Clary jump, but after cautious inspection, she realized he was still asleep. He was still wearing his weapons belt, but it had been loosened. Clary suddenly felt as if she was being repressed within herself, as if another side of her was taking over. She struggled half-heartedly with it, but it was too strong, controlling her actions and thoughts. A wickedly sharp dagger slipped from Sebastian's belt into her hand. An awful, harsh voice rasped in her mind, _first, cut his wrist, then drink his blood. We must be closer to him_. As her hand moved towards Sebastian's bare arm, the voice chanted, _closer, closer, closer_.

Clary bit her lip hard, trying to stop the moving hand with the other, but it was to no avail, and blood trickled from a shallow, horizontal cut on the inside of his wrist. At the sight of Sebastian's dark blood, Clary moaned, pulling his wrist to her mouth. She sucked greedily on his blood, savouring the sweet richness. Her nails bit into his skin as her hands circled his wrist, pumping the blood from his veins.

Sebastian's eyes flew opened, and quite suddenly, Clary found herself flung beneath him, the dagger pressed to her throat, his muscles tense, ready to strike. When he realized who it was, he smirked, returned the knife to his belt, and murmured, "Did your bloodsucker teach you that?"

At that moment, Clary snapped out of her dream-like state, and cowered away from him, thinking he would be angry at her. She stuttered, "S-Seb! I-I…I was just, I mean, I—"

He stroked the hair off her face, interrupting her to say soothingly, "Sshh, if you needed my blood you should have just asked! Are you still hungry?"

"I didn't get that much…" She muttered, eyeing the blood that had begun to congeal on his wrist. Sebastian laughed a rich, honeyed laugh, and extended a claw, slicing a second, deeper cut next to the existing one. The blood from the second cut welled like a river compared to the dribble from the first. "Next time, you should cut deeper, little sister, then you will get more blood," he whispered, "You upset me yesterday, and I forgot to feed you. I am sorry, my dear, you must be starving."

His blood had trickled down his forearm, some of it creating a barely-there stain on the black sheets. Watching the blood flow and hearing Sebastian talk about _feeding_ and _hunger _repulsed Clary as she realized how disgusting it was. _She craved his blood? _His wrist moved closer to her mouth and she twisted away from him. _No! I won't drink anymore of that vile stuff!_

Sebastian sensed her change in mood, "Not this again, Clarissa," he sighed. His voice slipped into the gentle, coaxing tone he used when he wasn't impatient enough to beat her into submission. But Clary found this worse than abuse, as it made her _want_ to submit to him. Because they were linked, when he was angry, she could feel his anger too, but found it easy to direct that anger at him, sparking her defiance. But when he exuded the silky calm he was now, she couldn't help but relax into a submissive little puppet.

"Clarissa," he said mellifluously, "Shhh, little one, look at me." His onyx eyes were soft, his gaze possessive. Clary found she couldn't keep her eyes away from his; they were captivatingly deep, inviting, pulling her in. She could feel herself sinking and drowning and melting, all at the same time, in the gentle, bottomless pools of black. Sebastian continued, "That's right, my sweet." He whispered, his voice growing softer, "It's just a glamour on my eyes, there's no need to tense up. Just relax now." Clary sank back into the pillows, his hand guiding her down. He held his wrist over her lips and said, "Drink, my dear, drink." And although it revolted her, she did.

When he deemed her "full", Sebastian scrawled an _iratze _on his arm and dropped the stele onto the bed next to him. The blood was already taking effect, sapping her energy. He pulled Clary's limp body against him, tucking her head to his chest, wrapping her in his warm embrace.

XxXxXxXxXxXxXxXxXxX

For the second time, Clary woke wrapped in the silky sheets of Sebastian's bed, to find him still asleep. She rolled onto her back, but shifted again, her hand searching for the object that was probing her moments ago. Her fingers clasped something cylindrical, long and smooth, cool to touch, like metal. Her heart yammered in her chest. Sebastian's stele! He must have left it there after healing himself!

Clary jumped out of bed as silently as possible, ran out into the corridor, and found what she was looking for. A large section of the wall was uninhibited by furniture, fittings or artworks. With reckless haste, she scribbled the portal rune, pictured the institute, and skipped through, free.


	5. Chapter 5

_Umm… home, HOME, HOME! _Clary pleaded, as she tumbled through the portal. She squeezed her eyes shut tightly, the acid in her stomach bubbling within her as if it were boiling. At first, it was like she was flying, but too high, her ears popping from the altitude. Then she was spinning, faster and faster and faster, cold freezing her from inside out. Clary opened her mouth to call out, but an invisible force pushed the air back inside her. She choked, struggling to breathe.

She felt nothing, except the strange force pushing at her from all directions. She was weightless and nauseated as the lack of oxygen began take its effect, a throbbing headache settling in. A room began to form in front of Clary, like a ghostly mirage surrounding her. Suddenly, the force left, all at once, dropping her onto the off-white carpet. She looked up to see familiar white walls, a bed with a colourful, unmade bedspread, very familiar drawings and sketches. _My bedroom! _She gasped. She'd made it!

Clary ran to the closed door, twisting the knob, calling out to her Mum, realising how much she wanted to see Jocelyn again. As she began to race through the flung-open door, she was wrenched backwards, pulled once again into the icy, empty limbo of the portal.

_Shit! Was I not concentrating hard enough on where I wanted to go? What's going to happen to me? Shit, shit, shit! Will I be stuck here forever?_

Another room materialised around Clary; this time, though, the force still smothered her, and she floated, as if part of the ceiling. It was the room she lived in at the institute, the one nearly identical to Jace's. _Jace! Oh God, Jace! How I've missed him!_

For the third time, she was sucked into the abyss, barely recovered, the vomit she'd just spewed up plastered to her clothes. When the spinning stopped, Clary was in the spare room at Luke's house; the house where many of her childhood memories were made. Of the three rooms, she was there for the shortest amount of time.

She plummeted; down, down, down, she squeezed her eyes closed, gulping great lungs full of air. When Clary opened them, she was in Sebastian's room.

XxXxXxXxXxXxXxXxXxX

"Did you enjoy your little trip then, sister?" Sebastian said, his voice dangerously soft.

Clary spun, backing—cowering—into the nearby corner; anywhere that was away from him. He stalked towards her, his hair mussed from sleep, and sparkling with water droplets from his obviously recent shower. He buttoned his shirt as he approached, sauntering, as if casually. _Why isn't he angry? Why isn't he punishing me?_ Clary thought fretfully.

"It was a lesson for you, little one, and a confirmation for me," Sebastian replied to her worried thoughts, "I left the stele out knowing you would try to escape. What were you thinking when you jumped through the portal?" He added when he reached her.

"Home," Clary whispered timidly. _He'll lash out suddenly, he won't be able to contain his anger for much longer, soon he'll explode, just you wait Clary! _She warned herself.

"And you saw several places before you landed back here?" Sebastian said, crouching in front of her, caging her in with outstretched arms on the walls either side of her head.

"Yes," She whispered even softer than before, cringing from him.

He curled the loose strands of her hair behind her ear, his voice charming as he murmured, "Don't you see now, little one? You belong with me. You wanted "Home" when you jumped through the portal, and after seeing all the possibilities, deep down, you chose me! I taught you—and confirmed for myself—that underneath your defensiveness, you made your home wherever I am, and you stand at my side," He leant in further to kiss her forehead, "You see it now, don't you Clarissa?"

"I—I need time to process it, Seb. It's too much," Clary sighed, staring at her vomit-ruined clothes.

"Good thing I ran a bath! You smell," He teased, wrinkling his nose daintily, holding his hand out to help her up. He led her to his en suite, then, with all seriousness returned, said, "I used to think you belonged to me; as if I could possess you. But I was wrong, little one. One day, when you are ready to be at my side, when you have forgotten Angel-boy and the others, you won't belong to me. You, Clarissa Adele Morgenstern, will belong _with_ me."

"_Forget them?_" Clary said, incredulously, "They love me! One day, soon, Sebastian, they will find me and rescue me and protect me and they'll never let you near me again!"

"In the unlikely event that that _actually_ happens, they won't protect you, Clarissa! **They will take you to the Clave the second the get their hands on you, and you know it!**"

"No, no, they wouldn't," Clary said, weakly.

"'Dura lex sed lex.' Do you think they really don't live by their motto, little one?" He said softly, "They wouldn't hesitate to turn you over if they thought you had any idea where I am. They aren't your friends. They will use you to get to me."

XxXxXxXxXxXxXxXxXxX

Clary vigorously scrubbed the stench of her vomit off her body with Sebastian's citrus soap, before sinking into the warm water. She felt her tension ebb away as the scent of her brother enveloped her.

_If I'm starting to want to be with Sebastian as he says, than the Change is happening faster than I anticipated. But is this really what I want? I hated him from the moment I realised he existed, but now I'm not sure what to think. To be honest, I can't say that I hate him entirely anymore…_An overwhelming surge of somnolence crashing through her, cutting off her train of thought. Clary closed her eyes, unable to do anything but pray she wouldn't drown.

Xx_Dream_Xx

**_CLARISSA ADELE MORGNSTERN!_**_A voice called, breaking through the infinite silence and darkness of her sleep. Wait…she knew that voice…_

_Magnus?_

**_Clary, thank God, I've been trying to reach you for days! Are you alright?_**

_I'm fine_

**_Unlikely, but we're coming to save you, Clary. I just need you to find out where you are, because Sebastian has put an anti-tracking spell on you._**

_I don't know where we are. But tell me, Magnus, when you find me, will you hand me over to the Clave?_

There was a pause, as if he was thinking of an answer. Then—

XxRealityXx

She woke suddenly, as if the connection had been broken. _He didn't answer me! _Clary thought, worrying her brother was right about her friends.

She wasn't sure how long the dream lasted, possibly hours, but when she had finally recovered from the shock of talking to Magnus, and emerged, her brother was in his study, waiting for her.

**AN: "Dura lex sed lex" is the (official) Clave motto, Latin for "the Law is hard, but it is the Law"**


	6. Chapter 6

Clary knocked on her brother's study door, first hesitantly, then louder when there was no response. There was a throaty groan, followed by Sebastian's pained voice calling out her name. Clary found herself shoving open the door and racing towards her brother at his desk. Sebastian was slumped over, his hands pressed to his chest, a dark crimson blossoming around the left side of his white collared shirt.

"Oh my God! Sebastian!" Clary gasped, pulling him upright. When her hand collided with his arm, a violent jolt swept through her. They jerked back from each other, Sebastian cursing loudly as he collapsed onto the floor. Through the shirt and his blood, the bonding rune which tied Jace to Sebastian glowed gold.

"_Stele, bottom drawer_," He groaned, his arm signalling erratically.

Clary ripped open the drawer and slashed Sebastian's shirt down its centre. She gasped. An approximately five centimetre incision was cut diagonally across the glowing bonding rune. Judging by the depth of the wound, Clary guessed it had been created by a heavy weapon, like a sword. She sketched an _iratze_ as close to the wound as she could, then a second rune for relieving pain next to it, hearing Sebastian sigh audibly in relief.

Then suddenly all the runes on his torso and arms began to sparkle like the bonding rune as if a golden fire was lit beneath his skin. Clary slid back and watched with bated breath as the 'fire' slowly diminished, leaving behind no trace of his runes. Sebastian slacked into the floor, his eyes closed and body limp.

"Seb?" Clary said hesitantly, and reached to poke his arm.

She received no response, and was about to prod harder when a violent force shoved her backwards and pinned her to the ground, so fast she didn't have time to make a noise. She attempted to wriggle out of the strong grip on her wrists, but Sebastian's strength was far greater than her own. Her darted to his, accusations and complaints ready on her tongue, when she realised his irises had expanded, covering the white bits completely. _His demon side_, Clary puzzled, _but why has it come out now?_

Then she was flipped—for the second time by her brother—unceremoniously onto her back. Sebastian yanked so hard at her shirt it tore. Clary yelped as his clawed fingers ran greedily over the rune he had inked on her previously. He cackled, making Clary cringe; she had grown to like his honeyed voice and rich laughter, but this demonic laugh sounded cruel and uncaring. _You are mine, Clarissa, my sweet sister! __**All mine!**_ He hissed inside her head, making her flinch.

"Are you scared of me, dearest sister?" He mocked, "A little sister shouldn't be afraid of her big brother; he's there to protect her". Clary struggled to breathe, Sebastian's weight crushed her small frame, and his fingers pressed her face into the ground stopping her from making a sound. She relaxed, realising she needed to focus on breathing, and really there was no point in struggling anyway.

Then suddenly Clary felt some of his weight leave her back and hands as he leant his head next to hers and murmured in his normal gentle voice, "Good, little one. That's right. Don't struggle." Clary's mind, it seemed, had gone into a kind of shock, and barely registered Sebastian's sudden switch from demon back to normal. But the small part of her that seemed to be attracted to him—which Clary thought of as her new demon side—had begun to respond, and she felt it begin to creep its way up through her.

Sebastian smiled, his lips curving up and brushing her ear. His breath on her skin was hot and not entirely unpleasant, as he began pressing his lips down the back of her neck, touching the sensitive skin there and making her shiver. His hands ran up and down her sides excitedly as he kissed the rune he'd placed on her. Clary felt the rune pulse and grow slightly warmer. Her demon side rose up in response and took control of her weak body. She felt a wave of strength run through her, then a second wave of deep attraction towards her brother. A loud, unrepressed moan sang from her lips.

With her newfound strength, she rolled over, then turned again, so she was resting on his stomach, and crashed her mouth against his. Their tongues collided against each other, and there was the metallic taste of blood as Sebastian bit down on her lip. They groaned deep in their throats, and Clary moved her hands hurriedly to rake his shirt up. His body was feverously warm, his hard, defined muscles tightening at her touch.

She felt a distinct bulge against her thigh, growing harder and pressing more insistently with each second. Clary's eyes flew open, to find Sebastian's lust-filled demon eyes consuming her. _He'd switched again!_

Normal, rational Clary scrambled off him, scooting backwards as fast as she could. Sebastian's eyes smouldered dangerously. "_You are mine, Clarissa! I Marked you as mine and __**you belong to me! I will take you whenever I choose and you will not resist!**_"

"I don't belong to you, I belong to myself!" Clary said, stalling for time as she backed towards the door.

"I claimed you as my mate. That means you are mine." Sebastian said void of emotion. Then suddenly he cried; "Now if anyone so much as lays a hair on you, I will know, and they will face my wrath!" He cackled with frenzied glee, pouncing at her suddenly.

Caught by surprise, Clary yelped, as the wind was knocked out of her. Sebastian slammed her into the ground, one hand restraining hers, the other moving down towards her jeans. He struggled for a second with undoing her belt buckle with one hand, then gave up and tore through her belt and jeans with an extended, wickedly sharp claw.

Clary sobbed, "No! No, no Sebastian! Please, please don't!"


	7. Chapter 7

Clary continued to struggle fruitlessly.

"No! Stop!" She cried, "Stop! You're hurting me!"

And suddenly, Sebastian froze. He sucked in a deep breath, his face contorted in pain. Then he sprang off her, and backed up until he was across the room from her. Clary slumped onto the ground, exhausted, but still wary. His expression was still one of great pain, but also regret and…compassion!?

"Clarissa," He whispered hoarsely, "Clarissa, I'm so sorry, I can't believe what I just did, I've—_It's_ never been so in control of me like this, I don't know what happened. Clary, I'm so sorry I hurt you—forced myself on you. I…I—"

"Stop, Sebastian. What are you talking about? Who's 'it'?" Clary interjected. She had never heard him like this, so torn. He was babbling. _Maybe he's gone mad, _she thought, _maybe he'll let me go home!_

"Ha-Have you, um..." He made a frustrated noise. _Is he lost for words? Wow! _"Basically, Clarissa, there are two halves of me, inside," he made a cutting motion across his body, "and one side is me—Jonathan—and the other side is it, the demon. I was born a Shadowhunter, and when Lilith's blood was introduced to my system the split was created. It's incredibly painful sometimes, when the Angel and Demon blood fight each other for dominance. But the Nephilim runes help me keep control of the demon, until now it seems." He slid down the wall and buried his head between his knees.

It took a minute or so for what he'd said to sink in with Clary. The shock had worn off now and she stood up, yanking her shirt down and holding her jeans where the fastening button was. "Where _are _your runes though? They just disappeared when I healed you"

He raised his head, and she saw—No! Where those _tears_ on his cheek!? "Thanks, for that by the way, Clary. I don't know what happened, one minute I was reading some papers, and the next I felt like I was on fire! My body was burning all over, especially from where the rune that bound Jace and I was. Then my runes started _aching_, and then…"

"They disappeared," Clary finished.

"Yeah," he sighed, standing and walking towards her.

A surge of panic shot through her and Clary bolted to the door and down the corridor to the kitchen.

"Clary! Clary, no, wait! I'm not going to hurt you just wait!" He called after her. She spun, and seeing that he was coming after her she screamed and ran towards the stairs.

"Clary, please! I'm not going to hurt you!" But he had followed her up the stairs; she could hear his heavy footsteps pounding up the steel staircase. Clary's eyes watered, and her head pounded. She had a sick sense of déjà vu; he had chased her around the last apartment, and this one too too, and she was trapped again, alone, with him.

There was nowhere she could go to escape him; she couldn't see anything that she could use as a weapon, there wasn't any time to hide. Then suddenly, she couldn't breathe. It was like something was squeezing her throat closed, she just couldn't get any air in! Clary felt herself falling, falling to the grey carpet. He head and eyes _throbbed. _She couldn't move, she couldn't breathe. She felt his hands on her; all Clary was aware of was that he was touching her.

"No! No! No!" She wanted to be as far away from him as possible, but she was paralysed.

His voice cut through the fog that saturated her, "Clarissa! Clarissa you need to stop panicking! Clary listen to me, you need to breathe!"

In her mind, manipulating her again; _Breathe! Breathe, Clary!_

Clary shuddered as she sucked in deep breaths of air. The oxygen flooded through her lungs and body, and immediately the fog around her began to dissipate.

When she could move, she pushed herself out of his arms, crawling pathetically down the corridor. "Don't touch me, Sebastian! Don't you dare touch me! Ever again, do you hear!?"

"Clarissa, Clary, I won't come near you if you don't want me to," he said, his voice cracked, "Clarissa, _I_ would never hurt you. It did all that, not me. I'm Jonathan, your brother, who I would've been entirely if Valentine hadn't screwed me up. I need to find a way to get rid of the demon, and think only you can help me."

"Why!? Why should I help you?" Clary shouted, letting all the disgust and hate pour into her voice.

"Because you're my sister and I'm not the demon. I truly want to get rid of it. Please say you'll help me, Clarissa, please?" He looked so helpless and defenceless. _God, _Clary thought, _what an act! So like Valentine._

Sebastian—Jonathan—whichever he was growled. "Please don't ever compare me to him," he bit out.

_Stay out of my thoughts, dickhead!_

"If you want me to trust you, then I want to make a deal," Clary acquiesced.

"Thank you, Clarissa."

"Jeez! It's Clary, okay?" She got to her feet stiffly, ignoring his outstretched hand, and moved with as much dignity as she could to her room at the end of the corridor.

At her doorway she turned, and saw Jonathan crumpled on the ground, the sound of his quiet crying reaching her, and a pang of pity and worry jolted her.

"Stop it! That isn't you thinking that!" Clary muttered to herself, forcing her body into the room.

XxXxX

Clary had one of the longest showers she'd ever had, scrubbing hard at her skin, until it was as raw and exposed as she felt. Hand-shaped bruises were already forming on her arms and legs, there were scratches on her face, neck and arms from his sharpened nails and teeth, and her lip was split.

After changing into new underwear, a pair of jeans and t-shirt from the well-stocked closet, Clary slumped to the floor and brushed her hair until it was unusually soft and manageable.

She imagined that she should feel enraged and destructive, but all she felt was _quiet_.

She sat for a long time, consumed by her warring thoughts. She shouldn't feel anything good or nice towards this monster, regardless of him being her brother, especially since he tried to rape her. But maybe it wasn't an act; maybe he really was telling the truth, and he had some kind of split personality thing going on. If that was the case, she would have to help him. But whether or not this whole thing was an act, Clary realised that the fastest way to get out of here would be to make the deal with him.


End file.
